This scifi movie centers around a group of convicts who are sent to a base (underground or in outer space?)Slowly each one of them winds up being killed and it is discovered one of the convicts or soldiers is actually an alien/mutant super soldier.

The only scene I really remember is a black woman being bitten in the neck by this alien/mutant in disguise.

I remember watching this in the 90's when SciFi was showing movies like Xtro 2 and Xtro 3

I did some digging thanks to you providing the 1997/1998 time frame for Habitat and Convict 726.

I seriously just went through the scifi tv schedule for each day of those years

I think the movie is called "Legion"I'm not positive though since I can't find a trailer or it uploaded anywhere.

"The story is set in the year 2036 and revolves around a special forces team led by Major Agatha Doyle (Farrell) formed, similarly to that of The Dirty Dozen, from death-row prisoners and their ensuing mission.

Captain Aldrich is a former war hero convicted and on death row who is offered the chance at a pardon if he will join the team and undertake their mission to infiltrate an enemy facility. Once they have gained access to the base they are confused by the apparent lack of resistance and upon further inspection they find their enemies bodies piled up in a storeroom.

Their state of mind is weakened when they are attacked and some of them are killed without seeing the perpetrator. After finding a computer disk holding information they listen to the account given by the enemy team commander about how events unfolded leading to their enemies demise. Finally it dawns on them that the unknown killer that picked their enemies off one by one is now stalking them.

The surviving members of Doyle's team have to try to destroy the demon enemy before it destroys them."

I watched a lot of Sci-Fi movies on the Sci-Fi Channel during that period. They referred to many as Sci-Fi Originals even back then. I hope you have found what you're looking for. Also recall watching stuff like Within the Rock and Ravager...I do suspect you likely caught it along with Habitat on Sci-Fi during that 1997-1998 period.